$this->db->select('clients.name, sites.name');
$this->db->from('clients');
$this->db->join('sites_table', 'clients.site_id = sites_table.site_id');
$this->db->join('sites', 'sites_table.site_id = sites.site_id');
$this->db->orderby('clients.name', 'DESC');
$query = $this->db->get();